Movable Type doesn’t have a content review system. You can write an entry and leave it in “Draft” status, but no one knows about it unless they go looking for it.
In practice, this can be a pain. New authors to Gadgetopia are told to leave their first dozen or so entries in Draft so they can be reviewed before being posted. This requires them to send an email with the entry title, for which other authors then have to go looking. This is tedious, and it adds friction to the publishing process.
Wouldn’t it be neat if MT could generate an email announcing that an entry is ready to be reviewed and include the entry text in the email so reviewers just have to respond wth their comments? Well, with a few modifications, it can.